Lenticular lens sheet including light-shielding layer and process of producing the same

ABSTRACT

A lenticular lens sheet having ( 1 ) a light-transmitting lens sheet body with a lenticular lens group formed of multiple lenticular lenses placed on a surface of the body and a silver salt emulsion light-shielding layer laminated to the other surface of the light-transmitting lens sheet body. Light-transmitting areas in the light-shielding layer correspond to light-converging parts of the lenticular lenses on the body. The positions of the light-shielding areas correspond to non-light-converging parts of the lenticular lenses. The light-shielding characteristics result from the darkened silver dispersed in the silver salt emulsion. A method for making the lenticular lens sheet is disclosed also.

TECHNICAL FIELD

The present invention relates to a lenticular lens sheet for use in arear projection screen. More particularly, it relates to a lenticularlens sheet including on its light-emerging surface side alight-shielding layer, and to a process of producing the same.

BACKGROUND ART

A so-called projection-type television, which an image is projected fromthe rear and the projected image is viewed from the front, is known as alarge-screen television. Such a projection-type television includes animaging light source and a rear projection screen for displaying thereonan image projected from the imaging light source. Currently used for theimaging light source are CRT's (cathode-ray tubes) for projection,characterized by higher luminance than that of ordinary CRT's, as wellas liquid crystal display (LCD) projectors, digital light processing(DLP) projectors using digital micro-mirror devices (DMD's), and thelike.

FIG. 7 is a view showing an example of a rear projection screen for usein a projection-type television. As shown in this figure, a rearprojection screen 10 is composed of a Fresnel lens sheet (Fresnel convexlens) 11 and a lenticular lens sheet 12, where an image projected froman imaging light source (not shown in the figure) located at the rear ofthe rear projection screen 10 (upside in the figure) is viewed by aviewer who is in front of the rear projection screen 10 (downside in thefigure). In the rear projection screen 10 shown in FIG. 7, when light 20emitted by the imaging light source (not shown in the figure) located atthe rear of the rear projection screen 10 (upside in the figure), therays of the light 20 spreading to a certain extent, enters the rearprojection screen 10, this incident light 20 is converged by the Fresnellens sheet 11 to become, for example, parallel rays 21. These parallelrays 21 are converged by lenticular lenses 13 that are provided on thelenticular lens sheet 12 on its light-entering surface side, and go outas emergent light 22 from the light-emerging surface side of thelenticular lens sheet 12 at an angle in the range θ. This angle range θis the range in which the projected image is visible.

As shown in FIG. 7, the lenticular lens sheet 12 for use in such a rearprojection screen 10 contains, on its light-emerging surface side, alight-shielding layer 14 in order to prevent reflection of extraneouslight (light that enters from the downside in FIG. 7) to improve imagecontrast. The light-shielding layer 14 has light-shielding areas (blackstripes) 14 a that correspond to the non-light-converging parts of thelenticular lenses 13. The light-shielding areas 14 a in thelight-shielding layer 14 can be created by coating, with a materialcapable of shielding light, those parts with a certain width of thelight-emerging surface of the lenticular lens sheet 12 that correspondto the non-light-converging parts of the lenticular lenses 13.

It is necessary to create the light-shielding areas 14 a in thelight-shielding layer 14 as large as possible in such positions that theincident light 20 projected from the rear does not go out, with highpositional accuracy relative to the lenticular lenses 13 having thefunction of converging the incident light 20. There is therefore a heavydemand for a method of accurately creating the light-shielding areas 14a in the light-shielding layer 14.

In recent years, an LCD or DLP projector, or the like has come to beused, instead of a CRT, in a projection-type television as an imaginglight source. An image projected from such a light source is composed ofdot matrixes and has sharper definition. For this reason, a so-calledfine-pitch lenticular lens sheet 12 with a lens pitch smaller than thatrequired for the magnifying projection of an image on a CRT has come tobe demanded. Specifically, as long as a CRT is used, it is enough forthe lenticular lenses to have a pitch between 0.5 mm and 2.0 mm, butwhen an LCD or DLP projector, or the like is used, the lenticular lensesare required to have a fine pitch between 0.05 mm and 0.3 mm.

The method described in Japanese Laid-Open Patent Publication No.120102/1997, for example, has been known as a method of creatinglight-shielding areas 14 a in a light-shielding layer 14 that is used ina fine-pitch lenticular lens sheet 12 of the above-described type. Inthis method, an ionizing-radiation-curing resin layer is formed on theflat surface of a lenticular lens sheet opposite to the lens-providedsurface (the surface on which lenticular lenses are formed), andultraviolet light is applied to the lenticular lens sheet from thelens-provided surface side to expose the ionizing-radiation-curing resinlayer, thereby curing those parts of the resin layer that are in thepositions corresponding to the light-converging parts of the lenticularlenses. Making use of the stickiness of the surfaces of those parts ofthe resin layer other than the cured parts, a toner or transfer inklayer (black in color) is adhered to the surfaces of those parts of theresin layer that are in the positions corresponding to thenon-light-converging parts of the lenticular lenses. A light-shieldinglayer having therein a predetermined light-shielding pattern is thusformed on the lenticular lens sheet on its light-emerging surface side.

However, the lenticular lens sheet produced by the method described inthe above publication is at a disadvantage in that the light-shieldingpattern in the light-shielding layer is poor in positional accuracy.Another drawback is as follows: the light-shielding effect of thelight-shielding layer is insufficient, so that when this lenticular lenssheet is combined with a light-converging lens means such as a Fresnellens sheet to make a rear projection screen, sufficiently high opticalefficiency cannot be obtained, and, in addition, it is highly possiblethat high image contrast cannot be obtained.

Further, in the method described in the above publication, the processof creating the light-shielding areas requires the step of forming anionizing-radiation-curing resin layer; the step of curing, by exposure,those parts of the resin layer that are in the positions correspondingto the light-converging parts of the lenticular lenses, leaving thesurfaces of the other parts of the resin layer sticky; the step ofadhering a toner or transfer ink layer to the non-light-convergingparts; and so forth. This method thus requires a large number of steps,so that it is poor in efficiency.

DISCLOSURE OF THE INVENTION

The present invention was accomplished in the light of theaforementioned drawbacks in the background art. An object of the presentinvention is therefore to provide a lenticular lens sheet that comprisesa light-shielding layer having a light-shielding pattern formed withhigh positional accuracy and that ensures sufficiently high imagecontrast even when it is combined with a light-converging lens meanssuch as a Fresnel lens sheet to make a rear projection screen, and aprocess of producing such a lenticular lens sheet.

Another object of the present invention is to provide a lenticular lenssheet for use in a rear projection screen, that comprises alight-shielding layer and that can be produced with higher efficiency,and a process of producing such a lenticular lens sheet.

The main feature of the present invention is that: the light-shieldinglayer that is formed on the lenticular lens sheet on its light-emergingsurface side is made from a silver salt emulsion (a silver saltphotosensitive material) which is widely used in the fields ofphotography and medical service. With the use of a silver saltphotosensitive film or the like, a silver salt emulsion layer islaminated to the light-emerging surface of the lenticular lens sheetopposite to its lens-provided surface (the surface on which lenticularlenses are formed). Exposure light is applied to the lenticular lenssheet from its lens-provided surface side to expose the silver saltemulsion layer, and development is then conducted to darken theunexposed parts of the silver salt emulsion layer, whereby alight-shielding layer with a predetermined light-shielding pattern isformed on the lenticular lens sheet on its light-emerging surface side.It is thus possible to obtain the light-shielding pattern of thelight-shielding layer with high positional accuracy. Further, it ispossible to vary the degree of darkening of the uncured parts accordingto the rate of exposure of the silver salt emulsion layer or to thedegree of development. Therefore, if the optical transmission density ofthe light-shielding areas in the light-shielding layer is madeespecially high, there can be obtained a lenticular lens sheet for usein a rear projection screen, having low reflectance for extraneouslight, that is, capable of attaining high image contrast.

Specifically, the present invention provides, as a first aspect, alenticular lens sheet comprising: a light-transmitting lens sheet bodyhaving a lenticular lens group consisting of multiple lenticular lensesarranged on one surface; and a light-shielding layer made from a silversalt emulsion, laminated to the other surface of the lenticular lenssheet body; wherein the light-shielding layer has light-transmittingareas in the positions corresponding to the light-converging parts ofthe lenticular lenses on the lens sheet body, and light-shielding areasthat are in the positions corresponding to the non-light-convergingparts of the lenticular lenses and that have light-shieldingcharacteristics owing to the darkened silver dispersed in the silversalt emulsion.

In the first aspect of the present invention, the light-shielding areasin the light-shielding layer have an optical transmission density ofpreferably 2 or more, more preferably 3 or more.

Further, in the first aspect of the present invention, the lens sheetbody is preferably a transparent, single-layer sheet with the lenticularlens group integrally shaped.

In the first aspect of the present invention, it is also preferable thatthe lens sheet body includes a transparent film, and a lenticular lenslayer with the lenticular lens group shaped, the lenticular lens layerbeing laminated to the transparent film.

In the first aspect of the present invention, it is also preferable thatthe light-shielding layer be laminated to the surface of the lens sheetbody opposite to the surface having the lenticular lens group, with atransparent film different from the lens sheet body being disposedbetween the lens sheet body and the light-shielding layer. Thetransparent film, to which the light-shielding layer is laminated, maybe laminated to the surface of the lens sheet body opposite to thesurface having the lenticular lens group with the use of an adhesiveagent layer.

In the first aspect of the present invention, it is also preferable thatthe lenticular lens sheet further comprises a plate-like supportingmember capable of transmitting light, the supporting member beinglaminated to the lens sheet body on the lenticular lens group side orthe light-shielding layer side.

In addition, in the first aspect of the present invention, it ispreferable that the outermost surface of the lenticular lens sheet onthe light-shielding layer side has a reflectance of not more than 10%.Further, it is preferable that the light-shielding areas in thelight-shielding layer have, for light of 700 nm, a spectral reflectance90 to 110% of that for light of 400 nm.

The present invention provides, as a second aspect, a process ofproducing a lenticular lens sheet, comprising the steps of: preparing alight-transmitting lens sheet body having a lenticular lens groupconsisting of multiple lenticular lenses arranged on one surface;laminating a silver salt emulsion layer to the other surface of thelenticular lens sheet body; applying exposure light to the lens sheetbody from the lenticular lens group side to expose those parts of thesilver salt emulsion layer that correspond to the light-converging partsof the lenticular lenses; and developing the silver salt emulsion layerto obtain a light-shielding layer having light-transmitting areas in thepositions corresponding to the light-converging parts of the lenticularlenses, and light-shielding areas that are in the positionscorresponding to the non-light-converging parts of the lenticular lensesand that have light-shielding characteristics owing to the darkenedsilver dispersed in the silver salt emulsion.

In the second aspect of the present invention, the silver salt emulsionlayer is developed so that the light-shielding areas in thelight-shielding layer can have an optical transmission density ofpreferably 2 or more, more preferably 3 or more.

Further, in the second aspect of the present invention, it is preferableto prepare, for the lens sheet body, a transparent, single-layer sheetwith the lenticular lens group integrally shaped.

Furthermore, in the second aspect of the present invention, the processfurther preferably comprises the steps of: preparing a mold roll forshaping lenticular lenses, whose periphery, serving as a mold face, isprovided with grooves in the inverse shape of the lenticular lens group;winding a transparent film around the mold face of the mold roll, withan ionizing-radiation-curing resin composition between the mold face ofthe mold roll and the transparent film; and applying ionizing radiationto the mold roll through the transparent film to cure theionizing-radiation-curing resin composition; whereby a sheet including atransparent film, and a lenticular lens layer with the lenticular lensgroup shaped, the lenticular lens layer being laminated to thetransparent film, is prepared for the lens sheet body.

In the second aspect of the present invention, it is preferable that thelamination of the silver salt emulsion layer to the surface of the lenssheet body opposite to the surface having the lenticular lens group beconducted by applying a silver salt emulsion to the former surface ofthe lens sheet body and drying the silver salt emulsion applied.

In the second aspect of the present invention, it is also preferablethat the lamination of the silver salt emulsion layer to the surface ofthe lens sheet body opposite to the surface having the lenticular lensgroup be conducted by backing a silver salt emulsion layer with atransparent film to obtain a silver salt photosensitive film andadhering this silver salt photosensitive film to the lens sheet body,with the transparent film of the photosensitive film facing the surfaceof the lens sheet body opposite to the surface having the lenticularlens group.

In the second aspect of the present invention, it is preferable to useparallel rays for the exposure light. It is herein preferable that theparallel rays have a parallelism of 0°. It is also preferable that theparallel rays have a parallelism of more than 0° and 10° or less. AFresnel printer, or a system composed of a light source and a louverthrough which light from the source can pass can be used as an exposuresystem capable of applying the parallel rays.

In the first aspect of the present invention, the light-shielding layerlaminated to the surface of the lens sheet body opposite to the surfacehaving the lenticular lens group is formed from a silver salt emulsion,and the light-transmitting areas and the light-shielding areas arecreated by patterning the light-shielding layer, making use of thedifference in the degree of darkening of silver dispersed in the silversalt emulsion. It is therefore possible to make the light-shieldingpattern in the light-shielding layer with high positional accuracy.Further, the light-shielding areas in the light-shielding layer canshield light thanks to the darkened silver dispersed in the silver saltemulsion, so that the reflection of extraneous light on the front(viewing plane) side can effectively be suppressed. It is thus possibleto obtain sufficiently high image contrast even when the lenticular lenssheet is combined with a light-converging lens means such as a Fresnellens sheet to make a rear projection screen.

Further, in the first aspect of the present invention, if the opticaltransmission density of the light-shielding areas in the light-shieldinglayer is made 2 or more, the light-shielding areas can surely show thelight-shielding effect. In addition, since the light-shielding areas inthe light-shielding layer have low reflectance, the reflectance forextraneous light on the front (viewing plane) side can be suppressed tolow.

Furthermore, in the first aspect of the present invention, if theoptical transmission density of the light-shielding areas in thelight-shielding layer is made 3 or more, the light-shielding areas canmore surely show the light-shielding effect. In addition, since thelight-shielding areas in the light-shielding layer have low reflectance,the reflectance for extraneous light on the front (viewing plane) sidecan be suppressed to lower.

Furthermore, in the first aspect of the present invention, if atransparent, single-layer sheet with a lenticular lens group integrallyshaped is prepared for the lens sheet body, it becomes possible tosimplify the structure of the lens sheet body.

Furthermore, in the first aspect of the present invention, if atransparent film, to which a lenticular lens layer having the lenticularlens group shaped is laminated, is prepared for the lens sheet body, itbecomes possible to make the lens sheet body with high accuracy andefficiency.

Furthermore, in the first aspect of the present invention, since thelight-shielding layer made from a silver salt emulsion may be laminatedto the lens sheet body with a transparent film different from the lenssheet body being disposed between the lens sheet body and thelight-shielding layer, a silver salt photosensitive film such as aconventional photographic silver salt film can be used to form thelight-shielding layer.

Furthermore, in the first aspect of the present invention, since thetransparent film, to which the light-shielding layer is laminated, maybe laminated to the lens sheet body with the use of an adhesive agentlayer, a silver salt photosensitive film such as a conventionalphotographic silver salt film can be used to form the light-shieldinglayer and can thus be readily fixed to the lens sheet body.

Furthermore, in the first aspect of the present invention, if thelenticular lens sheet further comprises a light-transmitting, plate-likesupporting member laminated to the lens sheet body on its lenticularlens group side or the light-shielding layer side, it becomesself-supporting and can well maintain its shape even when it is in thestanding state.

Furthermore, in the first aspect of the present invention, if theoutermost surface of the lenticular lens sheet on its light-shieldinglayer side is made to have a reflectance of not more than 10%, thelowering of image contrast that is caused by extraneous light can besuppressed to extremely small.

Furthermore, in the first aspect of the present invention, if thelight-shielding areas in the light-shielding layer are made to have, forlight of 700 nm, a spectral reflectance 90 to 110% of that for light of400 nm, they are seen black or nearly black and thus have lowered visualsensitivity. It is therefore possible to effectively prevent thelowering of image contrast that is caused by extraneous light.

According to the second aspect of the present invention, thelight-shielding layer having a predetermined light-shielding pattern isformed on the lens sheet body on its light-emerging surface side in thefollowing manner: a silver salt emulsion layer is laminated to thesurface of the lens sheet body opposite to the surface having thelenticular lens group; exposure light is applied to the lens sheet bodyfrom the lenticular lens group side to expose the silver salt emulsionlayer; and the silver salt emulsion layer is then developed to darkenits unexposed parts. It is therefore possible to produce a lenticularlens sheet comprising the light-shielding layer with higher efficiency.It is also possible to form the light-shielding pattern in thelight-shielding layer with high positional accuracy. In addition, thelight-shielding areas in the light-shielding layer can shield lightthanks to the darkened silver dispersed in the silver salt emulsion, sothat it is possible to effectively suppress the reflection of extraneouslight on the front (viewing plane) side. Sufficiently high imagecontrast can thus be obtained even when the lenticular lens sheet iscombined with a light-converging lens means such as a Fresnel lens sheetto make a rear projection screen.

In the second aspect of the present invention, if the silver saltemulsion layer is developed so that the light-shielding areas in thelight-shielding layer can have an optical transmission density of 2 ormore, the light-shielding areas can surely show the light-shieldingeffect. In addition, since the light-shielding areas in thelight-shielding layer have low reflectance, the reflectance forextraneous light on the front (viewing plane) side can be suppressed tolow.

Furthermore, in the second aspect of the present invention, if thesilver salt emulsion layer is developed so that the light-shieldingareas in the light-shielding layer can have an optical transmissiondensity of 3 or more, the light-shielding areas can more surely show thelight-shielding effect. In addition, since the light-shielding areas inthe light-shielding layer have low reflectance, the reflectance forextraneous light on the front (viewing plane) side can be suppressed tolower.

Furthermore, in the second aspect of the present invention, if atransparent, single-layer sheet with the lenticular lens groupintegrally shaped is prepared for the lens sheet body, it becomespossible to simplify the structure of the lens sheet body.

Furthermore, in the second aspect of the present invention, if atransparent film, to which a lenticular lens layer made from anionizing-radiation-curing composition is laminated, is prepared for thelens sheet body by the use of a mold roll for shaping lenticular lenses,whose periphery, serving as a mold face, is provided with grooves in theinverse shape of the lenticular lens group, it becomes possible to makethe lens sheet body with high accuracy and efficiency.

Furthermore, in the second aspect of the present invention, if thelamination of the silver salt emulsion layer to the lens sheet body isconducted by applying a silver salt emulsion to the lens sheet body, anddrying the silver salt emulsion layer applied, it becomes possible tomake the lamination structure of the finally obtained lenticular lenssheet simple.

Furthermore, in the second aspect of the present invention, if thelamination of the silver salt emulsion layer to the lens sheet body isconducted by adhering a silver salt photosensitive film prepared bybacking a silver salt emulsion layer with a transparent film, it ispossible to form the silver salt emulsion layer with higher accuracy.

Furthermore, in the second aspect of the present invention, if parallelrays are used for the exposure light, the light-shielding areas can beaccurately created in the light-shielding layer centered on thenon-light-converging parts of the lenticular lenses.

Furthermore, in the second aspect of the present invention, if theparallelism of the parallel rays is made 0°, it is possible toaccurately create, in the light-shielding layer, the light-shieldingareas with a preferable width.

Furthermore, in the second aspect of the present invention, if theparallelism of the parallel rays is made more than 0° and 10° or less,it is possible to create, in the light-shielding layer, thelight-shielding areas with the desired width.

Furthermore, in the second aspect of the present invention, if a Fresnelprinter is used as an exposure system capable of applying the parallelrays, it is possible to maintain the flatness of the lenticular lenssheet during exposure and thus to attain improved exposure accuracy.

Furthermore, in the second aspect of the present invention, if a systemcomposed of a light source and a louver through which light from thelight source can pass is used as an exposure system capable of applyingthe parallel rays, it is possible to conduct exposure while easilycontrolling the parallelism of the parallel rays.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is a cross-sectional view showing an embodiment of the lenticularlens sheet according to the present invention;

FIGS. 2A and 2B are cross-sectional views showing modifications of thelenticular lens sheet shown in FIG. 1;

FIGS. 3A and 3B are cross-sectional views showing other embodiments ofthe lenticular lens sheet according to the present invention;

FIG. 4 is a view for illustrating an example of the process of making alens sheet body, included in the process for producing a lenticular lenssheet according to the present invention;

FIG. 5 is a view for illustrating the process of making alight-shielding layer to be formed on a lens sheet body on itslight-emerging surface side, included in the process for producing alenticular lens sheet according to the present invention;

FIG. 6 is a diagrammatic perspective view showing an example of anexposure system that is used in the exposure step in the process ofmaking a light-shielding layer shown in FIG. 5; and

FIG. 7 is a view showing an example of a rear projection screenincluding a lenticular lens sheet.

BEST MODE FOR CARRYING OUT THE INVENTION

By referring to the accompanying drawings, embodiments of the presentinvention will be described hereinafter.

FIG. 1 is a cross-sectional view showing a lenticular lens sheet 1according to an embodiment of the present invention. As shown in thisfigure, the lenticular lens sheet 1 contains a light-transmitting lenssheet body 2 having a lenticular lens group 3 consisting of multiplelenticular lenses 3 a arranged on its upper surface.

To the lower surface of the lens sheet body 2 taking the above-describedstructure is laminated a light-shielding layer 4 made from a silver saltemulsion in which a silver salt is dispersed in an emulsion (silver saltphotosensitive material). The light-shielding layer 4 haslight-transmitting areas 4 a in the positions corresponding to thelight-converging parts of the lenticular lenses 3 a on the lens sheetbody 2, and light-shielding areas 4 b that are in the positionscorresponding to the non-light-converging parts of the lenticular lenses3 a (the areas between the light-transmitting areas 4 a) and that havelight-shielding characteristics owing to the darkened silver dispersedin the silver salt emulsion. The light-shielding areas 4 b in thelight-shielding layer 4 have an optical transmission density ofpreferably 2 or more, more preferably 3 or more. Both thelight-transmitting areas 4 a and the light-shielding areas 4 b in thelight-shielding layer 4 are created by exposing and developing thesilver salt emulsion layer, as will be described later.

The lens sheet body 2 in the lenticular lens sheet 1 shown in FIG. 1 isa transparent, single-layer sheet with the lenticular lens group 3integrally shaped. However, the lenticular lens sheet of the presentinvention is not limited to this, and the lens sheet body 2 may be madeby laminating, to a transparent film 6, a lenticular lens layer 7 havinga lenticular lens group 3 consisting of multiple lenticular lenses 3 aarranged, as shown in FIG. 2A. To the lower surface of the lens sheetbody 2 of the lenticular lens sheet 1 shown in FIG. 2A, alight-shielding layer 4 having light-transmitting areas 4 a andlight-shielding areas 4 b is laminated as in the lenticular lens sheet 1shown in FIG. 1.

In the lenticular lens sheet 1 shown in FIG. 2A, the light-shieldinglayer 4 is directly laminated to the lower surface of the lens sheetbody 2. However, the lenticular lens sheet of the present invention isnot limited to this, and the light-shielding layer 4 may also belaminated to the lens sheet body 2, with a transparent film 8 differentfrom the transparent film 6 of the lens sheet body 2 being disposedtherebetween, as shown in FIG. 2B. In this method, a silver saltemulsion layer, which it is not easy to uniformly form by coating, canbe formed beforehand, by coating, on the transparent film 8 having noirregularities, so that it is possible to form a silver salt emulsionlayer with higher accuracy. The transparent films 6 and 8 are hereinfixed to each other with the use of an adhesive agent layer 9, as shownin FIG. 2B, or with a mechanical means. The structure of the lenticularlens sheet 1 shown in FIG. 2B can readily be attained by the use of asilver salt photosensitive film, such as a conventional photographicsilver salt film, produced by laminating a silver salt emulsion layer toa transparent film. When using a conventional photographic silver saltfilm, it is desirable to remove an antihalation layer, which is oftenprovided on the back surface of the silver salt film.

The structure of the lenticular lens sheet 1 shown in FIG. 2B (in whichthe light-shielding layer 4 is laminated to the lens sheet body 2, withthe transparent film 8 (and the adhesive agent layer 9, if necessary)being disposed therebetween) is also applicable to the lenticular lenssheet 1 shown in FIG. 1.

The lenticular lens sheet 1 shown in FIG. 1, 2A or 2B is in the form ofan extremely thin film, so that it is not self-supporting and cannotwell maintain its shape when it is in the standing state.

It is therefore preferable to laminate a relatively-thick,self-supporting, light-transmitting sheet or plate (plate-likesupporting member) 15 to the lens sheet body 2 on its light-shieldinglayer 4 side, preferably with the use of a transparent adhesive agentlayer 9 a, as shown in FIG. 3A. For the sheet or plate 15, alight-diffusing one can be used. Alternatively, a sheet or plate 15having, on one surface, a light-diffusing layer laminated, may be used.

A Fresnel lens sheet (Fresnel convex lens) 16, which is alight-converging lens means often used in combination with a lenticularlens sheet 1, may also be used as the plate-like supporting member. Inthis case, the Fresnel lens sheet 16 is laminated to the lens sheet body2 on its lenticular lens group 3 side, preferably with the use of atransparent adhesive agent layer 9 a, as shown in FIG. 3B.

Although not shown in the figure, the following structure is alsoacceptable: a Fresnel lens sheet (Fresnel convex lens) alight-converging lens means, is laminated to the lens sheet body 2 onits lenticular lens group 3 side, as shown in FIG. 3B, while alight-transmitting sheet or plate is laminated to the lens sheet body 2on its light-shielding layer 4 side opposite to the lenticular lensgroup 3 side, as shown in FIG. 3A. For this sheet or plate, alight-diffusing one, or a sheet or plate having, on one surface, alight-diffusing layer laminated, can be used as in the lenticular lenssheet shown in FIG. 3A.

In the lenticular lens sheet 1 shown in FIG. 1, 2A or 2B, the surface onthe light-shielding layer 4 side is the viewing plane and is to face toa viewer. It is preferable that this viewing plane has extremely lowreflectance for extraneous light. Specifically, it is preferable thatthe outermost surface of the lenticular lens sheet 1 on itslight-shielding layer 4 side has a reflectance of not more than 10%. Inthe case where a light-transmitting sheet or plate 15 is laminated tothe lenticular lens sheet 1 on its light-emerging surface side, as shownin FIG. 3A, it is preferable that the exposed surface of the sheet orplate 15 has a reflectance of not more than 10%.

Further, it is preferable that the light-shielding areas 4 b in thelight-shielding layer 4 be seen black or nearly black. Depending on thetype of the silver salt emulsion used, the light-shielding areas 4 b,darkened areas, may be seen reddish or bluish. In the visible lightrange, however, it is preferable that the light-shielding areas 4 b haveflat or nearly flat reflection characteristics (reflectance for lightversus wavelength of the light). Furthermore, according to the resultsof our studies, it is preferable that the light-shielding areas 4 b havea spectral reflectance, for light of 700 nm, 90 to 110% of that forlight of 400 nm. This is because, when this percentage is less than 90%,the light-shielding areas 4 b are seen slightly bluish, while when it ismore than 110%, they are seen slightly reddish. However, it has beenknown from our experiences that the reflectance of bluishlight-shielding areas 4 b is perceived lower than that of reddish ones.It is therefore considered that the acceptable range is wider when theabove percentage is less than 90% than when the percentage is in excessof 110%.

Preferably, the width of the light-shielding areas 4 b in thelight-shielding layer 4 is in the order of 0.3 p to 0.9 p when the pitchp of the lenticular lenses 3 a in the lenticular lens group 3 formed onthe opposite side of the light-shielding layer 4 is in the order of 50to 300 μm. The pitch of the lenticular lenses 3 a and the width of thelight-shielding areas 4 b may be properly determined, considering theuse of the lenticular lens sheet, shaping accuracy, and so forth.

Next, by referring to FIGS. 4 to 6, a process of producing thelenticular lens sheet 1 whose structure is as mentioned above will bedescribed hereinafter.

First of all, a process of making the lens sheet body 2 of thelenticular lens sheet 1 is described with reference to FIG. 4. Takenherein as an example to describe the process is a case where the lenssheet body 2 is composed of a transparent film 6 and a lenticular lenslayer 7, as shown in FIG. 2A or 2B. Incidentally, a lens sheet body 2 asshown in FIG. 1, which is a transparent, single-layer sheet with alenticular lens group integrally shaped, can be made by a shaping methodusing a mold or mold roll. In general, a lens sheet body 2 as shown inFIG. 2A or 2B can be made more accurately and efficiently than a lenssheet body 2 as shown in FIG. 1.

As shown in FIG. 4, a transparent film 6 made of a transparent plasticfilm or the like which serves as a base film is unwound from theright-hand side in the figure, and is fed between a shaping roll 32 anda press roll 31 that are juxtaposed with each other. The shaping roll 32rotates clockwise, while the press roll 31 rotates anti-clockwise.

Before the transparent film 6 gets between the shaping roll 32 and thepress roll 31, an ultraviolet-curing resin composition(ionizing-radiation-curing resin composition) 7 a is fed from adispenser 33 that is located diagonally above the shaping roll 32. Theultraviolet-curing resin composition 7 a, now held between the shapingroll 32 and the transparent film 6, is carried under the shaping roll32. The shaping roll 32 is a mold roll for shaping lenticular lenses,and has, on its periphery that serves as a mold face, a large number ofgrooves formed in parallel, in the inverse shape of the lenticular lensgroup consisting of multiple lenticular lenses arranged. The shapingroll 32 is usually metallic.

An ultraviolet irradiation system 34 is located under the shaping roll32 so that ultraviolet light can be applied upwardly to the shaping roll32. When ultraviolet light is applied with this system, theultraviolet-curing resin composition 7 a held between the shaping roll32 and the transparent film 6 cures, and the cured ultraviolet-curingresin composition 7 a is in the inverse shape of the grooves that areprovided on the mold face of the shaping roll 32. A lenticular lenslayer 7 having thereon a lenticular lens group is thus formed, and thereis finally obtained a lens sheet body 2 composed of the transparent film6 and the lenticular lens layer 7 laminated to the transparent film 6.

This lens sheet body 2, being wound around the shaping roll 32, iscarried to a peeling roll 35 located on the left-hand side of theshaping roll 32 in such a position that it can nip, together with theshaping roll 32, the lens sheet body 2, and is peeled from the shapingroll 32.

The similar results can be obtained even when an electron-beam-curingresin composition is used in place of the above-describedultraviolet-curing resin composition 7 a, and an electron beam isapplied by the use of an electron beam irradiation system instead ofapplying ultraviolet light with the use of an ultraviolet irradiationsystem.

Thereafter, a silver salt emulsion layer is laminated to thelight-emerging surface (opposite to the surface having the lenticularlens group 3) of the lens sheet body 2 prepared in the above-describedmanner, and is successively subjected to exposure and development. Alight-shielding layer 4 having light-transmitting areas 4 a andlight-shielding areas 4 b is thus formed on the lens sheet body 2 on itslight-emerging surface side.

FIG. 5 is a view for illustrating the process of making alight-shielding layer 4 that is formed on the lens sheet body 2 on itslight-emerging surface side. Production of a lenticular lens sheet 1whose structure is as shown in FIG. 2B is herein taken as an example todescribe the process. Basically the same process can be employed toproduce a lenticular lens sheet 1 whose structure is as shown in FIG. 1or 2A.

As shown in FIG. 5(a), a silver salt emulsion layer 10 is firstlylaminated to the above-prepared lens sheet body 2 on its light-emergingsurface side. Lamination of the silver salt emulsion layer 10 to thelens sheet body 2 is herein conducted in the following manner: a silversalt photosensitive film 5 is prepared by backing a silver salt emulsionlayer 10 with a transparent film 8, and is adhered to the lens sheetbody 2 with the use of an adhesive agent layer 9, with the transparentfilm 8 of the silver salt photosensitive film 5 facing the lens sheetbody 2. Alternatively, lamination of the silver salt emulsion layer 10to the lens sheet body 2 may also be conducted in the following manner:a silver salt emulsion is applied to the light-emerging surface of thelens sheet body 2 and is then dried to form a silver salt emulsion layer10 directly on the light-emerging surface of the lens sheet body 2.Obtainable in the latter manner is a lenticular lens sheet 1 whosestructure is as shown in FIG. 1 or 2A.

Next, parallel rays (exposure light) 40 are applied to the lens sheetbody 2 from the lenticular lens group 3 side (the lenticular lens layer7 side) in the direction vertical to the lens sheet body 2. As a result,those parts of the silver salt emulsion layer 10 that correspond to thelight-converging parts of the lenticular lenses 3 a are exposed becausethe focal point of each lenticular lens 3 a generally exists in thevicinity of the light-emerging surface of the lens sheet body 2.

Thereafter, the silver salt emulsion layer 10 exposed in theabove-described manner is developed. Specifically, when the silver saltemulsion layer 10 is of negative type, reversal development isconducted, while when it is of positive type, development suited to theformulation of the layer is conducted. Thus, there is formed alight-shielding layer 4 having light-transmitting areas 4 a in thepositions corresponding to the light-converging parts of the lenticularlenses 3 a and light-shielding areas 4 b that are in the positionscorresponding to the non-light-converging parts of the lenticular lenses3 a and that have light-shielding characteristics owing to the darkenedsilver dispersed in the silver salt emulsion.

In the above-described development step, the silver salt emulsion layer10 is fully developed to such an extent that the darkenedlight-shielding areas 4 b in the light-shielding layer 4 can have anoptical transmission density of preferably 2 or more, more preferably 3or more.

In the exposure step shown in FIG. 5(b), if a contact aligner is used toconduct exposure using parallel rays 40, there may be used, for example,a Fresnel printer which can make diffused light from a light source intoparallel rays. The use of a Fresnel printer makes it possible to conductexposure while keeping the lenticular lens sheet in contact with theexposure system (contact bake); the flatness of the lenticular lenssheet can thus be well maintained during exposure.

Further, to conduct exposure using parallel rays 40 with the use of aslit exposure system, a Fresnel lens capable of covering the slit widthmay be used as a means for making diffused light from a light sourceinto parallel rays. Furthermore, as shown in FIG. 6, it is also possibleto pass diffused light 39 from a light source 41 through a louver 42 inthe form of a lattice or the like, thereby letting the diffused light goout as parallel rays 40. In the method shown in FIG. 6, the parallelismof the parallel rays 40 can be controlled by varying the size ofopenings in the louver 42 and the height (the dimension in the directionin which light passes) of the louver 42. Such a louver 42 can also beused in combination with the above-described contact aligner.

The lenticular lenses 3 a on the lens sheet body 2 are usually designedso that their focal points come on the light-emerging surface of thelens sheet body 2. Therefore, when perfectly parallel rays are used forexposure, the exposed parts (light-transmitting areas 4 a) usually haveextremely small widths, and the light-shielding layer 4 thus has thelight-shielding areas 4 b in an increased proportion. If a lenticularlens sheet 1 including such a light-shielding layer 4 havinglight-shielding areas 4 b in a high proportion is incorporated in a rearprojection screen, the screen has, in an increased proportion, thoseparts that are shielded by the light-shielding areas 4 b in thelight-shielding layer 4, unless the imaging light source, projector, isa point light source, and it is thus highly possible that the screenbecomes dark. It is possible to increase the widths of thelight-shielding areas 4 b in the light-shielding layer 4 by varying theconditions that are employed in the development step; however, this wayof controlling the widths of the light-shielding areas 4 b is usuallycomplicated. It is therefore preferable to expose only the needed areasto prevent the light-shielding areas 4 b from undergoing a great changein width depending upon development conditions.

On the other hand, the light source for use in the above-describedcontact exposure using a Fresnel printer or slit exposure using a louveris in the shape of neither a dot nor a line and is in a certain sizeeven if it is small. Therefore, light from the light source has anintensity distribution over a certain range of angle owing to the sizeof the light source, and the light-shielding layer 4 can thus beprevented from having the light-shielding areas 4 b in a proportionhigher than required.

The parallel rays 40 to be used for exposure light may be perfectlyparallel ones, that is, parallel rays with a parallelism of 0°. Evenwhen the parallel rays are ideal rays with a parallelism of 0°, it ispossible to vary the widths of the light-shielding areas 4 b in thelight-shielding layer 4 by changing the angle of light incident on thelens sheet body 2 relative to the direction of the normal. Sun light canbe used as parallel rays with a parallelism of 0°.

The parallelism of the parallel rays may also be made more than 0° and10° or less. As long as the parallelism falls in this range, it ispossible to create, in the light-shielding layer 4, the light-shieldingareas 4 b with the desired width. The use of parallel rays with aparallelism of 3° to 7° is more preferred.

In the above-described embodiments, optional layers such as (1) a hardcoating, (2) an antireflection coating, (3) an anti-glaring coating, (4)an antistatic coating, and the like may further be laminated to thesurface of the lenticular lens sheet 1 on its light-shielding layer 4side, or this surface of the lenticular lens sheet 1 may be processed sothat it can have the functions of these optional layers. The abovelayers (1)-(4) may be laminated directly to the surface of thelight-shielding layer 4 or the like. Alternatively, the lamination ofthe optional layers may also be conducted by coating alight-transmitting sheet or plate with the optional layers and adheringthis sheet or plate to the light-shielding layer 4 or the like.

EXAMPLES

In the system shown in FIG. 4, a polyethylene terephthalate resin filmwith a thickness of 75 μm was used as the transparent film, and anultraviolet-curing resin composition was fed from a dispenser and wasshaped and cured to obtain a lens sheet body composed of the transparentfilm having, on one surface, lenticular lenses with a height ofapproximately 45 μm arranged densely with a pitch of 130 μm.

The following composites of two different types, Composites A and B,were prepared by the use of the lens sheet body made in theabove-described manner.

(Composite A)

A positive silver salt film (Duplicating Film “DC” manufactured by FujiPhoto Film, Co. Ltd., Japan) was prepared as the silver saltphotosensitive film. The non-emulsion-coated surface of this film(opposite to the surface having a silver salt emulsion layer laminated)was rubbed with cloth impregnated with an undiluted solution of acommercially available bleaching agent (“Kitchen Haiter” manufactured byKao Corporation, Japan) to remove the antihalation layer. A transparent,pressure-sensitive adhesive was then applied at a thickness of 10 μm tothe surface of the above-prepared lens sheet body opposite to thesurface having the lenticular lenses. With the use of a laminator, thepositive silver salt film whose antihalation layer had been removed wasthen adhered to the lens sheet body, with the non-emulsion-coatedsurface of the silver salt film facing the adhesive layer on the lenssheet body. There was thus obtained Composite A consisting of the lenssheet body and the positive silver salt film. Two sheets of Composite Awere prepared.

(Composite B)

On the light-emerging surface of the above-prepared lens sheet body, agelatin layer with a thickness of 1 μm was formed as a primer layer,followed by drying. To this primer layer, a positive silver saltphotosensitive emulsion (capable of giving a silver salt emulsion layercomparable to that in the above-described positive silver salt film) wasapplied at a thickness of 4 μm, and was dried. There was thus obtainedComposite B consisting of the lens sheet body and the silver saltemulsion layer. Two sheets of Composite B were prepared.

The above-obtained Composites A and B, two sheets of each, weresubjected to exposure of two different types as described below.

(Exposure of First Type)

A parallel ray Fresnel printer (“Film FL-3R-X” available from USHIOU-TECH INC., Japan) was prepared as the contact aligner. A sheet ofComposite A and a sheet of Composite B were respectively subjected tocontact exposure by exposing the lenticular lens group side of eachsheet. The total exposure energy was made approximately 1.2 mJ/cm².

(Exposure of Second Type)

A fluorescent tube capable of emitting ultraviolet light (“FL20SBL”manufactured by Philips Corporation) was set downwardly, and its lowerpart was covered with a louver whose each square opening had internaldimensions of 4 mm×4 mm and a height of 40 mm; this assembly was used asthe slit exposure system. A sheet of Composite A and a sheet ofComposite B were respectively subjected to slit exposure by passing themright under the slit exposure system at a rate of 3.5 mm/sec, with thelenticular lens group side facing up.

Thereafter, the above-exposed two sheets of Composite A and two sheetsof Composite B were respectively developed with a developer (“ND”manufactured by Fuji Photo Film Co., Ltd., Japan) under the conditionsthat the solution temperature and development time were 35° C. and 30seconds, respectively, and were immersed in water for termination.Subsequently, the sheets were subjected to fixing using a fixingsolution (“NF” manufactured by Fuji Photo Film, Co., Ltd., Japan), wherethe solution temperature and immersion time were made 30° C. and 30seconds, respectively. After fixing was completed, these sheets wereimmersed in hot water at 40° C. for 1 minute for washing, and were thendried by blowing air at 45° C. for 60 seconds.

(Results)

In the above-described manner, lenticular lens sheets whose structurewas as shown in FIG. 2B were obtained from Composite A, while lenticularlens sheets whose structure was as shown in FIG. 2A, from Composite B.

In each silver salt emulsion layer in Composite A or B, formed on thelight-emerging surface of the lens sheet body, light-transmitting areaswere created centered on the focal points of the lenticular lenses, andlight-shielding areas with a width of 110 μm were created in thepositions shifted from the light-transmitting areas by ½ of thelenticular lens pitch, irrespective of the type of exposure employed.

Further, the total light transmittance of each lenticular lens sheetfinally produced by the use of Composite A or B was 83% and that of eachlenticular lens sheet measured on the light-shielding layer side was 8%,irrespective of the type of exposure employed. These lenticular lenssheets were thus found to have excellent properties sufficient forlenticular lens sheets for use in rear projection screens.

What is claimed is:
 1. A lenticular lens sheet comprising: alight-transmitting lens sheet body having a lenticular lens groupconsisting of multiple lenticular lenses arranged on one surface; and alight-shielding layer made from a silver salt emulsion, laminated to theother surface of the lenticular lens sheet body; wherein thelight-shielding layer has light-transmitting areas in positionscorresponding to light-converging parts of the lenticular lenses on thelens sheet body, and light-shielding areas that are in positionscorresponding to non-light-converging parts of the lenticular lenses andthat have light-shielding characteristics owing to darkened silverdispersed in the silver salt emulsion; and the light-shielding areas inthe light-shielding layer have, for light of 700 nm, a spectralreflectance 90 to 110% of that for light of 400 nm.
 2. The lenticularlens sheet according to claim 1, wherein the light-shielding areas inthe light-shielding layer have an optical transmission density of 2 ormore.
 3. The lenticular lens sheet according to claim 1, wherein thelight-shielding areas in the light-shielding layer have an opticaltransmission density of 3 or more.
 4. The lenticular lens sheetaccording to any of claims 1 to 3, wherein the lens sheet body is atransparent, single-layer sheet with the lenticular lens groupintegrally shaped.
 5. The lenticular lens sheet according to claim 1,wherein the lens sheet body includes a transparent film, and alenticular lens layer with the lenticular lens group shaped, thelenticular lens layer being laminated to the transparent film.
 6. Thelenticular lens sheet according to claim 1, wherein the light-shieldinglayer is laminated to the surface of the lens sheet body opposite to thesurface having the lenticular lens group, with a transparent filmdifferent from the lens sheet body being disposed between the lens sheetbody and the light-shielding layer.
 7. The lenticular lens sheetaccording to claim 6, wherein the transparent film, to which thelight-shielding layer is laminated, is laminated to the surface of thelens sheet body opposite to the surface having the lenticular lens groupwith use of an adhesive agent layer.
 8. The lenticular lens sheetaccording to claim 1, further comprising a plate-like supporting membercapable of transmitting light, the supporting member being laminated tothe lens sheet body on the lenticular lens group side or thelight-shielding layer side.
 9. The lenticular lens sheet according toclaim 1, wherein the outermost surface of the lenticular lens sheet onthe light-shielding layer side has a reflection of not more than 10%.10. A process of producing a lenticular lens sheet, comprising the stepsof: preparing a light-transmitting lens sheet body having a lenticularlens group consisting of multiple lenticular lenses arranged on onesurface; laminating a silver salt emulsion layer to the other surface ofthe lenticular lens sheet body; applying exposure light to the lenssheet body from the lenticular lens group side to expose those parts ofthe silver salt emulsion layer that correspond to light-converging partsof the lenticular lenses; and developing the silver salt emulsion layerto obtain a light-shielding layer having light-transmitting areas inpositions corresponding to the light-converging parts of the lenticularlenses, and light-shielding areas that are in positions corresponding tonon-light-converging parts of the lenticular lenses and that havelight-shielding characteristics owing to darkened silver dispersed inthe silver salt emulsion, said light-shielding areas in thelight-shielding layer having, for light of 700 nm, a spectralreflectance 90 to 110% of that for light of 400 nm.
 11. The process ofproducing a lenticular lens sheet according to claim 10, wherein thesilver salt emulsion layer is developed so that the light-shieldingareas in the light-shielding layer have an optical transmission densityof 2 or more.
 12. The process of producing a lenticular lens sheetaccording to claim 10, wherein the silver salt emulsion layer isdeveloped so that the light-shielding areas in the light-shielding layerhave an optical transmission density of 3 or more.
 13. The process ofproducing a lenticular lens sheet according to claim 10, wherein atransparent, single-layer sheet with the lenticular lens groupintegrally shaped is prepared for the lens sheet body.
 14. The processof producing a lenticular lens sheet according to claim 10, furthercomprising the steps of: preparing a mold roll for shaping lenticularlenses, whose periphery, serving as a mold face, is provided withgrooves in an inverse shape of the lenticular lens group; winding atransparent film around the mold face of the mold roll, with anionizing-radiation-curing resin composition between the mold face of themold roll and the transparent film; and applying ionizing radiation tothe mold roll through the transparent film to cure theionizing-radiation-curing resin composition; whereby a sheet including atransparent film, and a lenticular lens layer with the lenticular lensgroup shaped, the lenticular lens layer being laminated to thetransparent film, is prepared for the lens sheet body.
 15. The processof producing a lenticular lens sheet according to claim 10, wherein thelamination of the silver salt emulsion layer to the surface of the lenssheet body opposite to the surface having the lenticular lens group isconducted by applying a silver salt emulsion to the former surface ofthe lens sheet body and drying the silver salt emulsion applied.
 16. Theprocess of producing a lenticular lens sheet according to claim 10,where in the lamination of the silver salt emulsion layer to the surfaceof the lens sheet body opposite to the surface having the lenticularlens group is conducted by backing a silver salt emulsion layer with atransparent film to obtain a silver salt photosensitive film andadhering this silver salt photosensitive film to the lens sheet body,with the transparent film of the silver salt photosensitive film facingthe surface of the lens sheet body opposite to the surface having thelenticular lens group.
 17. The process of producing a lenticular lenssheet according to claim 10, wherein parallel rays are used for theexposure light.
 18. The process of producing a lenticular lens sheetaccording to claim 17, wherein the parallel rays have a parallelism of0°.
 19. The process of producing a lenticular lens sheet according toclaim 17, wherein the parallel rays have a parallelism of more than 0°and 10° or less.
 20. The process of producing a lenticular lens sheetaccording to claim 17, wherein a Fresnel printer is used as an exposuresystem capable of applying the parallel rays.
 21. The process ofproducing a lenticular lens sheet according to claim 17, wherein asystem composed of a light source and a louver through which light fromthe light source can pass is used as an exposure system capable ofapplying the parallel rays.